The spermatogenesis of pale chub (Zacco platypus) was investigated morphologically. The testis of pale chub contained numerous testicular sacs. These testicular sacs were bounded on neighboring sacs by single layer of squamous cells. Also, differentiated sperms were filled in the sacs. In the stage of spermatogonium, the germ cells had a large nucleus and a distinct nucleolus, and mitochondrial development was prominent. In the primary and secondary spermatogonia, these cells had a round electron-dense nucleus, reduced cytoplasm, and mitochondria were congregated in the side of cytoplasm. The highly condensed chromatin of sperms was electron-dense, the acrosome was not found in the head of the sperm and a motile flagellum consisted of an axoneme with a typical 9+2 pattern of microtubules.